From http://www.personal-growth-with-corinne-edwards.com/sales-102-the-hot-button/
Customers lie because they really don't know what their motivation is. Therefore, they do not tell you what they really want and why. It is your job to find out what that is. If you engage them in friendly conversation and LISTEN carefully, they will reveal it.
This reason is called their "hot button". Your job is to uncover this hidden reason. Then, to keep pushing that button.
There is always some hidden motivation that will prompt a person to buy. You have to listen to find it.
This also applies when you are interviewing for a job. Listen to what the prospective employer is looking for and then apply your transferrable skills exactly to that.